Color processing system and apparatus

Abstract

A color processing system includes a color interpolation unit coupled to receive color and white (W) signals and accordingly generate interpolated white signals and difference signals; a color correction unit configured to correct the difference signals, thereby resulting in corrected color signals; and a sensitivity control unit configured to generate adjusted color signals according to the corrected color signals, the interpolated white signals, and surrounding illumination.

What is claimed is:  
     
       1. A color processing system, comprising:
 a color interpolation unit coupled to receive color and white (W) signals and accordingly generate interpolated white signals and difference signals; 
 a color correction unit configured to correct the difference signals, thereby resulting in corrected color signals; and 
 a sensitivity control unit configured to generate adjusted color signals according to the corrected color signals, the interpolated white signals, and surrounding illumination; 
 wherein the sensitivity control unit comprises:
 an illumination estimator configured to estimate surrounding illumination; 
 a white gain generator configured to generate a gain value according to an output from the illumination estimator such that the less the surrounding illumination is, the greater the gain value is and vice versa; 
 a multiplier configured to multiply the interpolated white signal by the gain value; and 
 an adder configured to add an output of the multiplier to the corrected color signal, thereby generating the adjusted color signals. 
 
 
     
     
       2. The system of  claim 1 , wherein the color signals comprise a red (R) signal, a green (G) signal and a blue (B) signal; and the difference signals comprise W−R signal, W−G signal and W−B signal. 
     
     
       3. The system of  claim 1 , wherein the color interpolation unit comprises:
 a white interpolation subunit configured to generate the interpolated white signals according to the white signals; and 
 a difference signal generating subunit configured to generate the difference signals according to the interpolated white signals and the color signals. 
 
     
     
       4. The system of  claim 3 , wherein the difference signal generating subunit generates the difference signal by interpolation on neighboring difference signals. 
     
     
       5. The system of  claim 1 , wherein the color interpolation unit comprises:
 a white interpolation subunit configured to generate the interpolated white signals according to the white signals; 
 a color interpolation subunit configured to generate interpolated color signals according to the color signals; and 
 a subtractor configured to subtract the interpolated color signals from the interpolated white signals, thereby generating the difference signals. 
 
     
     
       6. The system of  claim 1 , wherein the output of the illumination estimator is an illumination measure generated by multiplying an integration time of an image sensor by a gain of the image sensor and then divided by a mean value of the white signals. 
     
     
       7. The system of  claim 6 , wherein the gain value is zero when the illumination measure is below a first threshold; the gain value is one when the illumination measure is above a second threshold that is greater than the first threshold; and the gain value monotonically increases from zero at the first threshold toward one at the second threshold. 
     
     
       8. A color processing apparatus, comprising:
 an infrared(IR)-cut filter coupled to filter a transmitted light, the IR-cut filter passing visible wavelengths and infrared wavelengths while blocking other wavelengths, thereby resulting in IR-cut filtered light; 
 a color and white filter array, which is composed of color filters and white filters, configured to filter the IR-cut filtered light, thereby resulting in color and white light; 
 an image sensor composed of photo sensors configured to convert the color and white light to color signals and white (W) signals, respectively; 
 a color interpolation unit coupled to receive the color and white signals and accordingly generate interpolated white signals and difference signals; 
 a color correction unit configured to correct the difference signals, thereby resulting in corrected color signals; and 
 a sensitivity control unit configured to generate adjusted color signals according to the corrected color signals, the interpolated white signals, and surrounding illumination; 
 wherein the sensitivity control unit comprises:
 an illumination estimator configured to estimate surrounding illumination; 
 a white gain generator configured to generate a gain value according to an output from the illumination estimator such that the less the surrounding illumination is, the greater the gain value is and vice versa; 
 a multiplier configured to multiply the interpolated white signal by the gain value; and 
 an adder configured to add an output of the multiplier to the corrected color signal, thereby generating the adjusted color signals. 
 
 
     
     
       9. The apparatus of  claim 8 , wherein the color and white light has a wavelength spectrum ranging from 380 nm to 1000 nm. 
     
     
       10. The apparatus of  claim 8 , wherein the color and white light has a wavelength spectrum including a visible band ranging from 380 nm to 700 nm, and a notch-shaped infrared band separated from the visible band. 
     
     
       11. The apparatus of  claim 8 , further comprising a lens, through which an incident light is transmitted, thereby resulting in the transmitted light. 
     
     
       12. The apparatus of  claim 8 , wherein the color signals comprise a red (R) signal, a green (G) signal and a blue (B) signal; and the difference signals comprise W−R signal, W−G signal and W−B signal. 
     
     
       13. The apparatus of  claim 8 , wherein the color interpolation unit comprises:
 a white interpolation subunit configured to generate the interpolated white signals according to the white signals; and 
 a difference signal generating subunit configured to generate the difference signals according to the interpolated white signals and the color signals. 
 
     
     
       14. The apparatus of  claim 13 , wherein the difference signal generating subunit generates the difference signal by interpolation on neighboring difference signals. 
     
     
       15. The apparatus of  claim 8 , wherein the color interpolation unit comprises:
 a white interpolation subunit configured to generate the interpolated white signals according to the white signals; 
 a color interpolation subunit configured to generate interpolated color signals according to the color signals; and 
 a subtractor configured to subtract the interpolated color signals from the interpolated white signals, thereby generating the difference signals. 
 
     
     
       16. The apparatus of  claim 8 , wherein the output of the illumination estimator is an illumination measure generated by multiplying an integration time of an image sensor by a gain of the image sensor and then divided by a mean value of the white signals. 
     
     
       17. The apparatus of  claim 16 , wherein the gain value is zero when the illumination measure is below a first threshold; the gain value is one when the illumination measure is above a second threshold that is greater than the first threshold; and the gain value monotonically increases from zero at the first threshold toward one at the second threshold.